1. Field of the Invention
This invention relates to a device for mounting a removable dental bridge or denture.
A removable dental bridge presents special problems in order to obtain sufficient cohesive force between the interengaged surfaces in the area to be bridged, high strength, long life, good hygiene, and to inhibit damage to living tissues and bone. In particular, it is difficult to obtain a balance of rigidity and flexibility insuring positive stabilization without damage to soft tissue and bone adjacent the area to be bridged. If the support is too rigid, the abutment, tissue and supporting bone structure can be damaged. If the support is too loose, then the denture may be inadvertently dislodged, causing inconvenience and embarrassment to the wearer.
It is not possible to increase size, strength and reliability of the mounting hardware substantially due to the space limitations. Moreover, bridge connectors are generally not easily adjusted to compensate for wear or minor changes in the features of the area to be bridged.
Therefore what is needed is a bridge connection structure which successfully overcomes the problems mentioned hereinabove, and particularly what is needed is an improved low cost system for mounting a removable dental bridge, denture or the like more acceptable to the intended application than devices heretofore known.
2. Description of the Prior Art
Dental clips are known for securing dentures and partial dentures to bars. One such system well-known in the art is the Dolder bar and clips. The Dolder bar comprises a rod having an egg-shaped transverse cross-section, and the clip comprises an open tubular segment having a horseshoe-shaped transverse cross-section.
The Dolder clip is subject to undersired loosening from the bridge piece into which it is embedded because the clip has no means for securing the clip to the material of the bridge piece other than the smooth outer surfaces of the clip walls. Moreover, the structure lacks provision respecting control of flexure of the side walls, which is potentially a problem should adjustment be required.
Another mounting system known to the art is the Ackermann bar and clip. The Ackermann bar may be either round or egg-shape in transverse cross-section. Of particular interest is the Ackermann clip. It comprises an open tubular segment having a horseshoe shape in cross-section, but it is characterized by a flare at the margins of the outer sides and by laterally disposed retention wings. The retention wings are tapered segments cut from the sides of the clip. The Ackermann clip and bar are intended to attach in a manner allowing a certain amount of play between parts of the prosthetic device.
The Ackermann clip is however subject to shortcomings. For example, the lateral retention wings, being tapered, do not always firmly seat in the acrylic material which is typically the compositon of the bridge piece. Furthermore, the wings, being formed by cut-outs from the sides of the clips, appear to weaken the clip sides somewhat. The cavities resulting from the cut-outs are also subject to accumulation of debris, which require special cleaning attention. A further significant limitation of the Ackermann clip is the difficulty of mounting the Ackermann clip in a relatively narrow prosthetic device. The wings have been found to interfere with normal investing (molding) processes. The wings must therefore be cut off or so severely bent as to be rendered ineffective to firm seating in the acrylic mold material.
A further example of a device for mounting a dental bridge is found in U.S. Pat. No. 3,429,043. Therein a bridge mounting device is described comprising a bar having a rectilinear transverse cross-section and a corrugated surface which is adapted to be mounted under tension between interfaces of a relatively rigid sleeve. Such a device does not provide for play or for adjustment, and therefore appears to be subject to the problems of loosening with age and wear and damage to tissue and the like, as hereinabove discussed.